WO2019111661A1

WO2019111661A1 - Liquid-feeding screw compressor

Info

Publication number: WO2019111661A1
Application number: PCT/JP2018/042100
Authority: WO
Inventors: 正彦高野; 茂幸頼金
Original assignee: 株式会社日立産機システム
Priority date: 2017-12-08
Filing date: 2018-11-14
Publication date: 2019-06-13
Also published as: US20200386231A1; US11313370B2; EP3722610A4; JPWO2019111661A1; TWI681123B; TW201925628A; EP3722610A1; CN111417784A; JP6862576B2; CN111417784B

Abstract

This liquid-feeding screw compressor is provided with: a casing that accommodates a screw rotor and a bearing, and that has an air intake and an intake chamber connected to the air intake; an intake throttle valve that is installed at the air intake, and that has a housing; and an intake air bypass system communicating between a primary side and a secondary side of the intake throttle valve. The intake air bypass system comprises: an intake air bypass channel that is provided to a wall section of the housing and comprises a primary-side opening that opens to a primary side of the intake throttle valve and a secondary-side opening that opens to a secondary side; and a first check valve arranged within the intake air bypass channel. The intake air bypass channel has an external opening that opens to the exterior of the housing, and allows for insertion and withdrawal of the first check valve. Due to this configuration, it is possible to make a system that communicates with an intake chamber in a casing and that is provided with a check valve mechanism into a pipeless structure, without compromising on the advantages of an external tubing.

Description

Liquid feed screw compressor

The present invention relates to a liquid feed screw compressor that supplies liquid into a working chamber for lubrication, cooling, sealing, and the like.

The screw compressor has a rotating screw rotor and a casing that accommodates the screw rotor and forms a plurality of working chambers with the screw rotor, and the working chamber is in the axial direction of the rotor as the screw rotor rotates. By moving, the gas (for example, air) in the working chamber is compressed. On the suction side of the casing, a suction throttle valve that opens and closes for adjusting the intake amount of the compressor or adjusting the load is provided.

Among screw compressors, there is a liquid supply type that supplies a liquid such as oil or water into the working chamber for the purpose of cooling compressed gas, lubricating a screw rotor, sealing a gap between a screw rotor and a casing, etc. . In the liquid feed screw compressor, when the drive is stopped, the compressed gas on the discharge side (high pressure side) in the casing instantaneously flows back to the suction side (low pressure side) due to the pressure difference. With the back flow of the compressed air, the liquid (liquid supplied to the working chamber) contained in the compressed gas flows back to the suction chamber in the casing and is scattered. At this time, the suction throttle valve is fully closed to prevent the liquid from leaking to the primary side (the upstream side of the suction throttle valve) of the suction throttle valve.

By the way, a plurality of systems including piping exposed to the outside of the casing (hereinafter referred to as "external piping") is connected to the casing. Some of these systems, including external piping, are in communication with the suction chamber in the casing. In the system of external piping communicating with the suction chamber, when the liquid scatters into the suction chamber at the time of driving stop of the compressor, the liquid may intrude into the system (in the external piping) and flow back. However, some of these systems have problems when liquid intrudes into the system and flows back. In such systems, a check valve is usually installed in the system to prevent backflow of liquid.

As a system of external piping provided with a check valve and communicating with the suction chamber, for example, there is a system for recovering lubricating oil that leaked from a shaft seal device provided on a screw rotor (see, for example, Patent Document 1). The screw rotor of the liquid feed screw compressor has a structure in which a shaft on one side extends to the outside of the casing in order to connect with a rotational drive source such as an electric motor. A bearing for supporting the screw rotor is disposed in the casing, and is lubricated to lubricate the bearing. A shaft seal device is provided on the shaft portion on one side thereof in order to prevent the lubricating oil from leaking out of the gap between the screw rotor and the casing. However, lubricating oil may leak slightly from this shaft seal device. Therefore, in the screw compressor described in Patent Document 1, a recovery pipe, which is an external pipe, is provided for recovering the lubricating oil that has leaked from the shaft sealing device, and this recovery pipe is used as a primary side and secondary side of the suction throttle. It connects so as to be communicated with the two spaces, and a non-return mechanism is provided on the recovery pipe on the secondary side.

Further, as another example of a system of external piping provided with a check valve and communicated with the suction chamber, for example, a system of external piping for securing a pressure source for driving a suction throttle valve at the time of startup of the compressor ( Hereinafter, it will be referred to as “system of respiratory piping”. Specifically, as shown in FIG. 7, the system BS of the breathing pipe P communicates with the housing H of the suction throttle valve V so that one side communicates with the space (suction flow path I) on the primary side of the suction throttle valve V. The other side is connected to the casing C so as to communicate with the space on the secondary side of the suction throttle valve V (the suction chamber R in the casing C), and is exposed to the outside of the housing H and the casing C. Since the suction throttle valve V is closed at the start of the compressor, the gas in the suction flow path I on the primary side of the suction throttle valve V passes through the system BS of the breathing pipe P and the secondary side of the suction throttle valve V It is introduced into the suction chamber R in the casing C. This intake air is compressed by the compressor body, and the compressed gas is used as a pressure source for operating the suction throttle valve V. The system BS of the breathing pipe P is a non-return valve for preventing the liquid splashed in the suction chamber R at the time of driving stop of the compressor from flowing back into the system BS and leaking to the primary side of the suction throttle valve V It has a mechanism CV.

The recovery system for lubricating oil in the screw compressor described in Patent Document 1 includes a recovery pipe (external pipe) exposed to the outside of the casing and a non-return mechanism installed on the recovery pipe. In such a configuration, even if a failure occurs in the non-return mechanism itself, the non-return mechanism can be removed from the collection pipe and easily replaced. In addition, when liquid such as lubricating oil is stagnant in the vicinity of the non-return mechanism, the function of the non-return mechanism may be impaired. However, since the recovery pipe is an external pipe, the installation position of the nonreturn mechanism on the recovery pipe can be easily changed in order to suppress the occurrence of such a nonreturn failure. The system BS of the breathing pipe P described above is also a system of external piping exposed to the outside of the housing H of the suction throttle valve V similarly to the recovery system of lubricating oil, and therefore has the same advantages as the recovery system of lubricating oil doing. Thus, in the system of the external piping, there is an advantage of ensuring the reliability of the check valve and the ease of replacing the check valve.

JP 2001-173585

However, in the above-described external piping system, there is a concern that the external piping may be cracked due to the vibration of the compressor. Further, since a plurality of joints (F1, F2 and F3 in FIG. 7) are required to connect the external piping and the non-return mechanism to the casing etc., there is a problem that the number of parts is large and the cost is high. In addition, if a large number of external pipes are installed, the locations where dust and dirt adhere are also increased, which may be disadvantageous in terms of equipment maintenance and the like. Furthermore, spatial occupancy by the external piping has a high risk of breakage due to a collision even when moving the compressor body, etc., and there is a disadvantage in handling. Therefore, there is a need for a pipeless structure for a system including a check valve in communication with the suction chamber in the casing without losing the advantage of the external piping.

The present application includes a plurality of means for solving the above problems, and an example thereof is a screw rotor for compressing a gas, a bearing for rotatably supporting the screw rotor, the screw rotor and the bearing And a casing having a suction port for sucking in gas and a suction chamber connected to the suction port, and a suction throttle valve installed at the suction port and having a housing forming a suction flow passage communicating with the suction port An intake bypass system for communicating the primary side and the secondary side of the suction throttle valve, wherein the intake bypass system is provided on a wall of the housing and is opened at the primary side of the suction throttle valve; An intake bypass channel having an opening and a second opening opened to the secondary side, and the primary side of the suction throttle valve disposed in the intake bypass channel And a first check valve for blocking the flow from the secondary side to the primary side of the suction throttle valve while permitting the flow to the secondary side, and the intake bypass flow path is provided outside the housing It is characterized by having a 3rd opening which is open and can insert and extract said 1st nonreturn valve.

According to the present invention, the intake bypass passage communicating the primary side and the secondary side of the intake throttle valve is provided on the wall of the housing of the intake throttle valve, and the first check valve is disposed in the intake bypass passage. Since the first check valve can be inserted and removed through the third opening of the intake bypass channel that opens to the outside of the housing, the intake bypass system can be pipeless without losing the advantage of the external piping. can do.
Problems, configurations, and effects other than those described above will be apparent from the description of the embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS It is a front view which shows the liquid supply type screw compressor which concerns on one embodiment of this invention in the state of a partial cross section. It is a side view of the liquid feeding type screw compressor concerning one embodiment shown in FIG. FIG. 3 is a cross-sectional view of a portion of the liquid feed screw compressor according to the embodiment shown in FIG. 2 as viewed in the direction of arrows III-III. It is sectional drawing which looked at the liquid supply type screw compressor which concerns on one Embodiment shown in FIG. 2 from IV-IV arrow. It is sectional drawing shown in the state which expanded the suction | inhalation bypass system of the liquid supply type screw compressor which concerns on one Embodiment shown to code | symbol V of FIG. It is sectional drawing shown in the state which expanded a part of oil recovery system of the liquid feeding type screw compressor which concerns on one Embodiment shown to code | symbol VI of FIG. It is a front view which shows the conventional liquid supply type screw compressor in the state of a partial cross section.

Hereinafter, an embodiment of a liquid feed screw compressor according to the present invention will be described by way of example with reference to the drawings.
[One embodiment]
First, the configuration of a liquid feed type screw compressor according to an embodiment of the present invention will be described using FIGS. 1 to 4. FIG. FIG. 1 is a front view showing a liquid supply type screw compressor according to an embodiment of the present invention in a partially sectional view. FIG. 2 is a side view of the liquid feed screw compressor according to the embodiment shown in FIG. FIG. 3 is a cross-sectional view of a portion of the liquid feed type screw compressor according to the embodiment shown in FIG. 2 as viewed in the direction of arrows III-III. FIG. 4 is a cross-sectional view of the liquid feed type screw compressor according to the embodiment shown in FIG. 2 as viewed from the arrow IV-IV.

1 and 2, the liquid feed screw compressor includes a compressor body 1 for compressing a gas such as air, and a suction installed on the suction side (upper side in FIGS. 1 and 2) of the compressor body 1 A throttle valve 2 is provided.

As shown in FIGS. 3 and 4, the compressor body 1 has a male rotor 4 and a female rotor 5 which are screw rotors having a plurality of helical teeth, and a casing 6 for housing the male rotor 4 and the female rotor 5. Is equipped. The male rotor 4 and the female rotor 5 rotate while their rotational axes are parallel and mesh with each other. A plurality of working chambers are formed between the male rotor 4 and the female rotor 5 and the casing 6. As the working chamber moves in the axial direction of the rotor as the male rotor 4 and the female rotor 5 rotate, the gas in the working chamber is compressed. In the working chamber, cooling of compressed gas in the working chamber, lubrication of both the male and

female rotors

4, 5, clearance between the tips of the male and

female rotors

4, 5 and the inner wall of the main casing 21, A liquid such as oil or water is supplied for the purpose of sealing the gap of the meshing portion.

The male rotor 4 is, as shown in FIG. 3, a rotor tooth portion 8 having a plurality of male teeth, and a shaft portion 9 integrally provided on both sides in the axial direction of the rotor tooth portion 8 (in FIG. And consists of. The shaft portion 9 on the suction side of the male rotor 4 extends outside the casing 6 in order to connect with the rotation shaft of a rotational drive source such as an electric motor. The male rotor 4 is rotatably supported by the suction side bearing 10 and the discharge side bearing (not shown). The suction side bearing 10 and the discharge side bearing are accommodated in the casing 6. Lubricating oil is supplied to the suction side bearing 10 and the discharge side bearing. A shaft seal device 12 for sealing a gap with the casing 6 is provided at the suction side shaft portion 9. The shaft seal device 12 prevents the leakage of the lubricating oil supplied to the suction side bearing 10 to the outside of the casing 6. For example, a mechanical seal is used as the shaft sealing device 12.

The female rotor 5 is composed of a rotor tooth portion 14 having a plurality of female teeth, and a shaft portion 15 integrally provided on both sides in the axial direction of the rotor tooth portion 14 (only the suction side is shown in FIG. 3). The female rotor 5 is rotatably supported by the suction side bearing 16 and the discharge side bearing (not shown), and is configured to rotate while meshing with the male rotor 4 as the male rotor 4 rotates. The suction side bearing 16 and the discharge side bearing (not shown) are accommodated in the casing 6. A lubricating oil is supplied to the suction side bearing 16 and the discharge side bearing.

As shown in FIG. 2, the casing 6 includes a main casing 21 and a discharge side casing 22 which covers the discharge side (right side in FIG. 2) of the main casing 21.

In the main casing 21, as shown in FIG. 4, two cylindrical bores 26 partially overlapping are formed, and in the bores 26, a male rotor 4 and a female rotor 5 are accommodated. As shown in FIGS. 1 and 4, a suction port 27 for sucking in gas is provided on the outer peripheral portion of the main casing 21, and a suction throttle valve 2 is installed at the suction port 27. A suction chamber 28 connected to the suction port 27 is formed inside the main casing 21. The suction chamber 28 communicates with the bore 26 and is a space through which the gas sucked from the suction port 27 flows to the working chamber of the intake stroke. As shown in FIG. 3, suction

side bearing chambers

29 and 30 for holding the

suction side bearings

10 and 16 are provided at axial end portions on the suction side of the main casing 21. The suction

side bearing chambers

29 and 30 and the bore 26 are separated by a partition 31. A suction side cover 23 that covers the suction

side bearing chambers

29 and 30 is attached to the main casing 21. The suction side cover 23 accommodates the shaft sealing device 12. The main casing 21 is provided with a liquid supply passage (not shown) for supplying liquid to the working chamber.

As shown in FIG. 4, a scattering cover 32 is provided in the suction chamber 28 in the casing 6 so as to cover the meshing portion between the male rotor 4 and the female rotor 5. In the liquid feed screw compressor, compressed gas in the working chamber is generated from the gap between the meshing portion of the male rotor 4 and the female rotor 5 due to the pressure difference between the high pressure side working chamber and the low pressure side working chamber during operation. The liquid contained therein spouts (arrow A in FIG. 4 indicates the spouted liquid). The scattering cover 32 suppresses the flow of the liquid ejected from the gap of the meshing portion toward the suction throttle valve 2 and suppresses the heating of the intake air by the ejected liquid. The scattering cover 32 also has a function of distributing the intake air flowing in from the suction port 27 of the casing 6 to the working chamber of the suction stroke on the male rotor 4 side and the working chamber of the suction stroke on the female rotor 5 side. The scattering cover 32 is formed, for example, in a concave shape (substantially U-shaped in cross section) toward the meshing portion, and is limited to a predetermined size so as not to be a resistance to intake.

In the discharge side casing 22 shown in FIG. 2, a discharge passage (not shown) for guiding the gas compressed in the working chamber to the outside, and a discharge side bearing (not shown) of the male rotor 4 and the female rotor 5 are held. Side bearing chambers (not shown) are provided respectively. A discharge side cover 24 covering the discharge side bearing chamber is attached to the discharge side casing 22.

In the present embodiment, the casing 6 is configured by the main casing 21, the discharge side casing 22, the suction side cover 23, and the discharge side cover 24.

The suction throttle valve 2 adjusts the suction amount of the compressor main body 1 according to, for example, the amount of compressed gas used by the customer. Further, in order to perform no-load operation control (unload operation control) for reducing the discharge side pressure while continuing the operation of the compressor body 1, the suction of the compressor body 1 is shut off. Further, when the driving of the compressor body 1 is stopped, leakage of the compressed gas flowing backward from the discharge side to the suction side of the compressor body 1 and the liquid contained in the gas to the upstream side is prevented. As shown in FIGS. 1 and 4, the suction throttle valve 2 includes a housing 41 forming the suction flow passage 42 and the cylinder 43, a valve seat 44 formed at the downstream end of the suction flow passage 42, and the cylinder 43. A piston 45 slidably disposed therein, which divides the inside of the cylinder 43 into a spring chamber 43a and an operation chamber 43b, and one end thereof is connected to the piston 45 and penetrates the cylinder 43 to the downstream side of the suction passage 42 (see FIG. In FIG. 1 and FIG. 4, the rod 46 extends downward, and the valve body 47 slidably inserted in the rod 46 and located on the downstream side of the valve seat 44 and capable of opening and closing the valve seat 44; A stopper portion 48 provided at the tip end portion of 46 and restricting the slide of the valve body 47 to the downstream side is provided, and a spring 49 disposed in a spring chamber 43 a in the cylinder 43. The suction flow channel 42 is, for example, a flow channel bent substantially at a right angle. The spring 49 applies, for example, a biasing force to the piston 45 to move the stopper portion 48 to the upstream side (upper side in FIGS. 1 and 4).

An operation pressure system (not shown) is connected to the operation chamber 43 b in the cylinder 43. The operation pressure system counteracts the biasing force of the spring 49 of the spring chamber 43a by introducing a part of the compressed air extracted from the compressed air system on the discharge side of the compressor body 1 into the operation chamber 43b in the cylinder 43. A pressure is applied to the piston 45 to move the stopper portion 48 downstream (downward in FIGS. 1 and 4). The operation pressure system includes, for example, a solenoid valve (not shown) opened and closed by a drive signal from a control device (not shown), and opening and closing of the solenoid valve causes the compressed air to be supplied to the operation chamber 43b in the cylinder 43 Adjust the input.

By the way, when the compressor is started, the pressure is reduced in the compressed air system on the discharge side of the compressor body 1, which is a pressure source for operating the suction throttle valve 2. So, in this embodiment, in order to secure the operation pressure of suction throttle valve 2 at the time of compressor start, intake bypass system 60 which bypasses suction throttle valve 2 in the closed state and introduces the intake air to compressor main body 1 Is equipped. Details of the intake bypass system 60 will be described later.

Further, in the shaft seal device 12 provided on the suction side shaft portion 9 of the male rotor 4 shown in FIG. 3, the lubricating oil supplied to the

suction side bearings

10 and 16 may slightly leak. Therefore, in the present embodiment, as shown in FIG. 1 and FIG. 4, an oil recovery system for collecting the lubricating oil leaked from the shaft sealing device 12 into the secondary side (suction chamber 28 of the casing 6) of the suction valve 2. It has 80. Details of the oil recovery system 80 will be described later.

Next, the details of the intake bypass system of the liquid feed screw compressor according to the embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. 5 is a cross-sectional view showing an enlarged intake bypass system of the liquid feed screw compressor according to the embodiment shown by symbol V in FIG. 1. In FIG. 5, the same reference numerals as those shown in FIGS. 1 to 4 denote the same parts, so the detailed description thereof will be omitted.

As shown in FIGS. 4 and 5, the intake bypass system 60 includes the suction flow path 42 (primary side of the suction throttle valve 2) of the suction throttle valve 2 and the suction chamber 28 (secondary of the suction throttle valve 2) in the casing 6. And a first check valve 62 disposed in the intake bypass channel 61. The intake bypass channel 61 is provided in the wall of the housing 41, and the first check valve 62 is disposed in the intake bypass channel 61.

The intake bypass passage 61 has, for example, a primary side opening 64 a that opens to the suction flow passage 42 side of the suction throttle valve 2 and a first external opening 64 b that opens to the outside of the housing 41. The first bypass passage hole 64 provided in the wall of the housing 41 so as to extend to the second side, the secondary side opening 65a opening to the suction chamber 28 side in the casing 6, and the outside of the housing 41 (2) A second bypass passage hole 65 provided in the wall portion of the housing 41 so as to have an outer opening 65b and extend linearly in the vertical direction and communicate with the first bypass passage hole 64 It is done. The first plug 66 is detachably attached to the first external opening 64 b of the first bypass passage hole 64. The second plug 67 is detachably attached to the second external opening 65 b.

The second bypass passage hole 65 has a large diameter portion 70 having a second external opening 65 b, a middle diameter portion 71 adjacent to the large diameter portion 70, and a secondary side opening portion 65 a adjacent to the middle diameter portion 71. It is comprised with the small diameter part 72 which it has. The large diameter portion 70 is larger in diameter than the first check valve 62. The medium diameter portion 71 is smaller in diameter than the large diameter portion 70 and slightly larger in diameter than the first check valve 62. The small diameter portion 72 is smaller in diameter than the first check valve 62. That is, the second bypass passage hole 65 is a two-step stepped hole. The middle diameter portion 71 is a portion where the first check valve 62 is disposed. The small diameter portion 72 regulates movement of the first check valve 62 to the suction chamber 28 side. The second outer opening 65 b of the large diameter portion 70 enables insertion of the first check valve 62 into the middle diameter portion 71 and removal thereof from the middle diameter portion 71. The large diameter portion 70 is formed in a hole diameter that facilitates insertion and removal of the first check valve 62.

The first bypass passage hole 64 can be formed by forming a lateral hole penetrating the wall of the housing 41 from the side outer surface of the housing 41 to the suction passage 42. The second bypass passage hole 65 is provided with a first vertical hole penetrating from the upper outer surface of the housing 41 to the suction chamber 28, and the second vertical hole having a larger diameter than the first vertical hole is a first vertical hole And the third vertical hole having a larger diameter than the second vertical hole coaxially with the first vertical hole and shorter than the second vertical hole. It is possible to form.

The first check valve 62 permits the flow from the suction flow passage 42 side to the suction chamber 28 side, and blocks the flow from the suction chamber 28 side to the suction flow passage 42 side. That is, in the first check valve 62, the liquid backflowing from the discharge side of the compressor main body 1 to the suction chamber 28 when the operation of the compressor is stopped leaks to the primary side of the suction throttle valve 2 via the intake bypass channel 61. To prevent that. A retaining ring 74 and an O-ring 75 are attached to the outer peripheral portion of the first check valve 62. The retaining ring 74 regulates movement of the first check valve 62 in the middle diameter portion 71. The O-ring 75 is to prevent the leakage flow from the gap between the outer peripheral surface of the first check valve 62 and the inner wall surface of the intake bypass channel 61. The first check valve 62 can be replaced by accessing through the second external opening 65 b of the large diameter portion 70 of the second bypass passage hole 65. In the replacement of the first check valve 62, the second plug 67 closing the second external opening 65b is removed, and a tool, for example, is used.

In the intake bypass system 60 configured as described above, the linear first bypass passage hole 64 and the second bypass passage hole 65 are drawn into the wall of the housing 41 of the throttle valve 2 to form the intake bypass passage 61. It is possible to easily manufacture the intake bypass channel 61. Further, as compared with the case where an intake bypass system (external pipe) is configured by connecting a pipe with a check valve to the housing 41 of the suction throttle valve 2, a joint that connects the pipe and the pipe to the housing 41, a check valve There is no need for fittings to attach to the piping.

By the way, when a liquid such as oil remains in the first check valve 62, the responsiveness of the valve body of the first check valve 62 may be reduced due to the influence of the liquid, which may cause a non-return failure. As described above, in the liquid feed screw compressor, during operation, the pressure difference between the high pressure side working chamber and the low pressure side working chamber causes the liquid contained in the compressed gas in the working chamber to be the male rotor 4 and the female. It spouts to the suction chamber 28 in the casing 6 from the gap of the meshing portion of the rotor 5. In this embodiment, since the intake bypass system 60 is built in the housing 41, the liquid spouted into the suction chamber 28 may enter the intake bypass channel 61 and stay in the vicinity of the first check valve 62. There is sex. In this case, it is impossible to prevent the backflow of the liquid from the suction chamber 28 to the primary side of the suction throttle valve 2 via the intake bypass passage 61 when the driving of the compressor is stopped due to the non-return failure of the first check valve 62 I am concerned.

Therefore, in the present embodiment, in the suction chamber 28 of the casing 6, the first shielding portion 76 is interposed between the secondary side opening 65a of the intake bypass passage 61 and the meshing portion of the male and

female rotors

4 and 5. It is provided. The first shielding portion 76 prevents the liquid ejected from the meshing portion during the operation of the compressor from intruding into the intake bypass channel 61. As a specific structure, for example, the first shielding portion 76 is disposed on a line from the meshing portion between the male rotor 4 and the female rotor 5 to the secondary side opening 65 a of the intake bypass channel 61, It projects from the wall portion of the main casing 21 toward the suction chamber 28 so as to cover the secondary side opening 65 a in a separated state.

Next, the details of the oil recovery system of the liquid feeding screw compressor according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4 and FIG. FIG. 6 is a cross-sectional view showing an enlarged part of an oil recovery system of the liquid feed screw compressor according to the embodiment indicated by symbol VI in FIG. In FIG. 6, the same reference numerals as those shown in FIGS. 1 to 5 denote the same parts, so the detailed description thereof will be omitted.

As shown in FIGS. 1 and 3, the oil recovery system 80 includes a recovery groove portion 81 as an oil storage portion capable of temporarily storing the lubricating oil leaked from the shaft sealing device 12, the recovery groove portion 81 and the inside of the casing 6. An oil recovery passage 82 communicating with the suction chamber 28 and a second check valve 83 disposed in the oil recovery passage 82 are provided. The recovery groove portion 81 is provided on the inner side surface of the suction side cover 23 along the outer peripheral surface side of the shaft portion 9 on the suction side of the male rotor 4.

The oil recovery flow path 82 is provided in the suction side cover 23 constituting a part of the casing 6 and the wall portion of the main casing 21 as shown in FIG. 1 to FIG. It has a side opening 85a and a collection side opening 88a that opens to the suction chamber 28 side. The oil recovery flow passage 82 includes, for example, a first recovery flow passage hole 85 communicating with the recovery groove portion 81, a second recovery flow passage hole 86 communicating with the first recovery flow passage hole 85, and a second recovery flow passage hole 86 The third recovery passage hole 87 communicates with the third recovery passage hole 87, and the fourth recovery passage hole 88 communicates with the third recovery passage hole 87 and the suction chamber 28 in the casing 6.

The first recovery passage hole 85 is provided in the wall portion of the suction side cover 23. The first recovery passage hole 85 has a storage side opening 85 a on the side of the recovery groove 81 and a third external opening 85 b opened to the outside of the suction side cover 23, and from the lowermost end of the annular recovery groove 81 It extends linearly in the tangential direction of the recovery groove portion 81. The third plug 90 is detachably attached to the third outer opening 85 b of the first recovery passage hole 85.

The second recovery passage hole 86 is provided in the suction side cover 23 and the wall portion of the main casing 21. The second recovery passage hole 86 has a fourth external opening 86 a opening to the outside of the suction side cover 23, and discharges along the axial direction of the male rotor 4 so as to intersect the first recovery passage hole 85. It extends linearly in the lateral direction. The fourth plug 91 is detachably attached to the fourth outer opening 86 a of the second recovery passage hole 86.

The third recovery passage hole 87 is provided in the wall portion of the main casing 21. The third recovery passage hole 87 has a fifth external opening 87a opened to the outside of the main casing 21, and the suction throttle valve 2 side from the end of the second recovery passage hole 86 (in FIGS. 2 and 4) , And linearly extending). The fifth plug 92 is detachably attached to the fifth outer opening 87 a of the third recovery passage hole 87.

The fourth recovery passage hole 88 is provided in the wall portion of the main casing 21 as shown in FIGS. 4 and 6. The fourth recovery passage hole 88 has a recovery side opening 88 a on the suction chamber 28 side and a sixth external opening 88 b opened to the outside of the main casing 21, and a third recovery flow at a position higher than the male rotor 4. It extends in a straight line in the horizontal direction so as to intersect the passage hole 87. The sixth plug 93 is detachably attached to the sixth outer opening 88 b of the fourth recovery passage hole 88.

The fourth recovery passage hole 88 is located on the outer side and has a large diameter portion 95 having a sixth outer opening 88b, a middle diameter portion 96 adjacent to the large diameter portion 95, and a suction chamber adjacent to the middle diameter portion 96. It is comprised by the small diameter part 97 which has the collection | recovery side opening part 88a of 28 side. The large diameter portion 95 is larger in diameter than the second check valve 83. The medium diameter portion 96 is smaller in diameter than the large diameter portion 95 and slightly larger in diameter than the second check valve 83. The small diameter portion 97 is smaller in diameter than the second check valve 83. That is, the fourth recovery passage hole 88 is a two-step stepped hole. The middle diameter portion 96 is a portion where the second check valve 83 is disposed. The small diameter portion 97 regulates movement of the second check valve 83 to the suction chamber 28 side. The sixth outer opening 88 b of the large diameter portion 95 enables insertion of the second check valve 83 into the middle diameter portion 96 and removal thereof from the middle diameter portion 96. The large diameter portion 95 is formed in a diameter that facilitates the insertion and removal of the second check valve 83.

The first recovery passage hole 85 can be formed by forming a lateral hole that penetrates the wall portion of the suction side cover 23 from the lateral outer surface of the suction side cover 23 to the lowermost end of the recovery groove portion 81. The second recovery passage hole 86 can be formed by drilling a horizontal hole of a predetermined length extending from the outer surface of the suction side cover 23 along the axial direction of the male rotor 4. The third recovery passage hole 87 can be formed by drilling a vertical hole to reach the end of the second recovery passage hole 86 from the upper outer surface of the main casing 21 downward. The fourth recovery passage hole 88 is provided with a first lateral hole penetrating from the side outer surface of the main casing 21 on the male rotor 4 side to the suction chamber 28 in the casing 6, and the hole diameter is larger than the first lateral hole. A second lateral hole is provided coaxially with the first lateral hole so as not to penetrate through the suction chamber 28, and a third lateral hole larger in diameter than the second lateral hole is coaxial with the first lateral hole. It can be formed by providing it shorter than the second horizontal hole.

The second check valve 83 allows the flow from the side of the collection groove 81 to the side of the suction chamber 28 and blocks the flow from the side of the suction chamber 28 to the side of the collection groove 81. That is, in the second check valve 83, the liquid flowing back from the discharge side of the compressor main body 1 to the suction chamber 28 when the driving of the compressor is stopped flows through the oil recovery passage 82 and the recovery groove portion 81 to the casing 6 (suction side cover 23) to prevent leakage to the outside. A retaining ring 99 and an O-ring 100 are attached to the outer peripheral surface of the second check valve 83. The retaining ring 99 regulates movement of the second check valve 83 in the middle diameter portion 96. The O-ring 100 is to prevent the leakage flow from the gap between the outer circumferential surface of the second check valve 83 and the inner wall surface of the oil recovery passage 82. The second check valve 83 can be replaced by accessing through the sixth outer opening 88 b of the large diameter portion 95 of the fourth recovery passage hole 88. In the replacement of the second check valve 83, the sixth plug 93 closing the sixth external opening 88b is removed, and a tool, for example, is used.

In the oil recovery system 80 configured as described above, the four first recovery passage holes 85, the second recovery passage holes 86, the third recovery passage holes 87, and the fourth recovery passage holes 88 in the linear form are arranged in the casing 6. Since the oil recovery channel 82 can be formed by piercing the wall, the oil recovery channel 82 can be easily manufactured. Moreover, compared with the case where an oil recovery system (external piping) is configured by connecting a pipe with a check valve to the casing 6, a pipe connecting the pipe and the pipe to the casing 6 and a joint connecting the check valve to the pipe Is unnecessary.

In the present embodiment, since the oil recovery system 80 is built in the casing 6, the liquid spouted into the suction chamber 28 intrudes into the oil recovery flow path 82 as in the first check valve 62 described above. There is a possibility of staying in the vicinity of the second check valve 83. In this case, there is a concern that the backflow of the liquid from the suction chamber 28 to the outside of the casing 6 via the oil recovery passage 82 can not be prevented when the driving of the compressor is stopped due to the non-return failure of the second check valve 83. .

Therefore, in the present embodiment, in the suction chamber 28 of the casing 6, the second shielding portion 101 is provided between the recovery side opening 88a of the oil recovery flow path 82 and the meshing portion of the male and

female rotors

4 and 5. ing. The second shielding portion 101 prevents the liquid (indicated by arrow A in FIG. 4) ejected from the meshing portion during operation of the compressor from intruding into the oil recovery flow path 82. As a specific structure, for example, the second shielding portion 101 is disposed on a line from the meshing portion between the male rotor 4 and the female rotor 5 to the recovery side opening 88a of the oil recovery flow path 82, It projects from the wall of the main casing 21 toward the suction chamber 28 so as to cover the side opening 88a in a separated state.

Next, each operation at the time of start-up, load operation, unload operation, and stop operation of the liquid feed type screw compressor according to the embodiment of the present invention will be described with reference to FIGS.

First, the operation at the start of the compressor will be described. At the time of start-up, the pressure of the pressure source for operating the suction throttle valve 2 is reduced, so that the suction throttle valve 2 shown in FIG. In this state, when the male rotor 4 and the female rotor 5 of the compressor body 1 are activated, an intake bypass provided on the wall of the housing 41 of the suction throttle valve 2 from the suction flow path 42 on the primary side of the suction throttle valve 2 A small amount of gas flows into the suction chamber 28 in the casing 6 which is the secondary side of the suction throttle valve 2 via the flow passage 61 and the first check valve 62 disposed in the intake bypass flow passage 61. The gas is compressed by the compressor body 1 and discharged to the outside of the compressor body 1. A portion of the discharged compressed gas is extracted and used as a pressure source for operating the suction throttle valve 2.

Thus, at the time of startup of the compressor, the intake bypasses the valve body 47 in the closed state of the intake throttle valve 2 and the suction in the casing 6 via the intake bypass channel 61 provided in the wall of the housing 41 Since it is introduced into the chamber 28, a pressure source for operating the suction throttle valve 2 can be secured at the start of the compressor.

Secondly, the operation during the load operation of the compressor will be described. During the loading operation, a portion of the air compressed in the high pressure side working chamber leaks into the suction chamber 28 from the gap between the meshing portion of the male rotor 4 and the female rotor 5 due to the pressure difference with the low pressure side working chamber. Do. As shown in FIG. 4, with the leakage of the compressed air, part of the high-temperature liquid contained in the compressed gas radially spouts from the meshing portion into the suction chamber 28. Among the liquid ejected from the meshing portion, the liquid ejected to the suction throttle valve 2 side (upper side in FIG. 4) is shielded by the scattering cover 32. For this reason, it is possible to suppress the heating of the intake air flowing from the suction throttle valve 2 into the suction chamber 28 by the high temperature liquid that has been jetted out. Therefore, the decrease in density due to the temperature rise of the intake air can be suppressed, and the decrease in performance of the compressor can be suppressed.

On the other hand, a part of the liquid ejected from the meshing portion (indicated by arrow A in FIG. 4) is not shielded by the scattering cover 32 and is scattered into the suction chamber 28. In the intake bypass system 60 according to the present embodiment, as shown in FIGS. 4 and 5, the first shielding portion 76 is provided to cover the secondary side opening 65a of the intake bypass passage 61 in a separated state. The entry of the splashed liquid into the intake bypass channel 61 is prevented. As a result, the first check valve 62 in the intake bypass channel 61 is not placed in the stagnant state of the liquid. Therefore, it is possible to prevent the occurrence of the non-return failure of the first check valve 62 due to the decrease in responsiveness due to the liquid.

Further, in the oil recovery system 80 according to the present embodiment, as shown in FIGS. 4 and 6, as in the intake bypass system 60, the recovery side opening 88a of the oil recovery passage 82 is covered in a separated state. The second shielding portion 101 provided prevents the scattered liquid from intruding into the oil recovery flow path 82. As a result, the second check valve 83 in the oil recovery channel 82 is not placed in the stagnant state of the liquid. Therefore, it is possible to prevent the occurrence of the non-return failure of the second check valve 83 due to the decrease in responsiveness due to the liquid.

Third, the operation during unloading operation of the compressor will be described. In the present embodiment, in order to recover the lubricating oil leaking from the shaft sealing device 12 to the suction chamber 28 (secondary side of the suction throttle valve 2) of the casing 6, the unloading operation is periodically performed.

Specifically, the pressure of the compressed air system on the discharge side of the compressor body 1 shown in FIG. 1 is reduced and the suction throttle valve 2 is completely closed. By continuing the rotation of both the male and

female rotors

4 and 5 in this state, the secondary side (the suction chamber 28 in the casing 6) of the suction throttle valve 2 has a negative pressure close to vacuum. On the other hand, as shown in FIG. 3, the recovery groove portion 81 storing the lubricating oil leaking from the shaft sealing device 12 has a clearance between the shaft portion 9 on the suction side of the male rotor 4 and the casing 6 (suction side cover 23). Since it is in communication with the outside of the casing 6, the pressure is substantially the same as the atmospheric pressure (usually atmospheric pressure) of the atmosphere outside the casing 6. Therefore, the lubricating oil stored in the recovery groove portion 81 is provided on the wall portion of the casing 6 shown in FIGS. 1 and 2 by using a differential pressure between the recovery groove portion 81 and the secondary side of the suction throttle valve 2 as a driving force. The oil is recovered in the suction chamber 28 in the casing 6 via the oil recovery flow path 82 and the second check valve 83 disposed in the oil recovery flow path 82. Thus, the lubricating oil leaking from the shaft sealing device 12 can be recovered to the secondary side of the suction throttle valve 2 by periodically performing the unloading operation.

Fourth, the operation at the time of driving stop of the compressor will be described. When the compressor being driven is stopped, the compressed gas on the discharge side of the compressor body 1 instantaneously flows back to the suction side due to the pressure difference. Furthermore, with the backflow of the compressed gas, the liquid contained in the compressed gas also flows back to the suction side at the same time.

At this time, the valve body 47 of the suction throttle valve 2 shown in FIG. 4 slides to the upstream valve seat 44 along the rod 46 by the compressed air flowing back to the suction chamber 28 in the casing 6, and the valve seat 44 is closed. Be done. That is, the suction throttle valve 2 is automatically closed by the backflowed compressed air. Thereby, the backflow of the compressed air and the liquid to the primary side of the suction throttle valve 2 at the time of the driving stop of the compressor is prevented.

Further, the compressed air that has flowed back into the suction chamber 28 tends to flow back to the suction flow path 42 (primary side of the suction throttle valve 2) of the suction throttle valve 2 via the intake bypass flow path 61. In the present embodiment, the reverse flow is blocked by the first check valve 62 disposed in the intake bypass passage 61. As described above, the liquid spouted into the suction chamber 28 during the load operation is unlikely to stay in the suction bypass channel 61. Therefore, the first check valve 62 is less likely to cause a drop in responsiveness due to liquid retention during load operation, and can respond to compressed air and liquid that instantaneously flows back to the suction chamber 28 side when the compressor is stopped. It is. That is, it is possible to prevent the backflow to the primary side of the suction throttle valve 2 of the compressed air that has flowed back into the suction chamber 28.

Further, the compressed air that has flowed back into the suction chamber 28 tends to flow back to the outside of the casing 6 (the suction side cover 23) via the oil recovery flow path 82. In the present embodiment, this backflow is blocked by the second check valve 83 disposed in the oil recovery flow path 82. As described above, the liquid spouted into the suction chamber 28 during the loading operation is unlikely to stay in the oil recovery flow path 82. Therefore, the second check valve 83 is less likely to cause a drop in responsiveness due to liquid retention during load operation, and can respond to compressed air and liquid that instantaneously flows back to the suction chamber 28 side when the compressor is stopped. It is. That is, it is possible to prevent the backflow of the compressed air flowing back into the suction chamber 28 to the outside of the casing 6.

According to one embodiment of the present invention, the suction passage 42 (primary side of the suction throttle valve 2) of the suction throttle valve 2 and the suction chamber 28 (secondary side of the suction throttle valve 2) in the casing 6 are communicated Of the intake bypass passage 61 provided in the wall of the housing 41 of the intake throttle valve 2, the first check valve 62 is disposed in the intake bypass passage 61, and opened to the outside of the housing 41. Since the first check valve 62 can be inserted and removed through the second external opening 65b, the intake bypass system 60 can be pipeless without losing the advantage of the external piping. Therefore, there is no need to worry about the occurrence of cracks due to compressor vibrations. Moreover, compared with the system of external piping, the reduction of a number of parts and the cost reduction accompanying it are possible. Furthermore, the pipeless structure reduces the spatial occupancy of the compressor body, reduces the possibility of breakage during movement, and also improves the convenience of handling.

Further, according to the present embodiment, the secondary side opening 65 a is covered in a separated state between the secondary side opening 65 a of the intake bypass flow passage 61 and the meshing portion of the male and

female rotors

4 and 5. As described above, since the first shielding portion 76 is provided, it is possible to suppress the entry of the liquid ejected from the meshing portion during the operation of the compressor into the intake bypass channel 61. Therefore, the stagnation of the liquid in the vicinity of the first check valve 62 disposed in the intake bypass flow passage 61 is suppressed, so that the non-return failure of the first check valve 62 can be prevented. That is, the reliability of the first check valve 62 can be reliably ensured.

Furthermore, according to the present embodiment, the linear second bypass passage hole 65 for arranging the first check valve 62 has the second outer opening 65 b and has a diameter larger than that of the first check valve 62. A large diameter portion 70 and an intermediate diameter portion 71 adjacent to the large diameter portion 70 and having a diameter smaller than the large diameter portion 70 and larger than the first check valve 62 and adjacent to the intermediate diameter portion 71; Since the small diameter portion 72 having a smaller diameter than the one check valve 62 is configured, the positioning of the first check valve 62 in the second bypass passage hole 65 is easy when the first check valve 62 is replaced. Also, the insertion and removal of the first check valve 62 through the second external opening 65 b is easy. That is, the first check valve 62 can be replaced very easily.

In addition, according to the present embodiment, two (plural) linear first bypass passage holes 64 and the second (two or more) having the

external openings

64b and 65b opened to the outside of the housing 41 of the suction throttle valve 2 and Since the intake bypass channel 61 is constituted by the bypass channel holes 65, the intake bypass channel 61 can be formed by forming a plurality of holes in the wall portion of the housing 41. Therefore, the manufacturing cost of intake bypass system 60 can be further reduced.

Further, according to the present embodiment, the oil recovery passage 82 communicating the recovery groove portion 81 (oil storage portion) with the suction chamber 28 is provided in the wall portion of the casing 6, and the second reverse Since the stop valve 83 is disposed and the second check valve 83 can be inserted and extracted through the sixth external opening 88 b of the oil recovery flow path 82 opened to the outside of the casing 6, the oil recovery system 80 A pipeless structure can be made without losing the advantage of the external piping. Therefore, there is no need to worry about the occurrence of cracks due to compressor vibrations. Moreover, compared with the system of external piping, the reduction of a number of parts and the cost reduction accompanying it are possible. Furthermore, the pipeless structure reduces the spatial occupancy of the compressor body, reduces the possibility of breakage during movement, and also improves the convenience of handling.

Furthermore, according to the present embodiment, the recovery side opening 88a is covered in a separated state between the recovery side opening 88a of the oil recovery flow path 82 and the meshing portion of the male and

female rotors

4 and 5. Since the second shielding portion 101 is provided, it is possible to suppress the entry of the liquid ejected from the meshing portion during the operation of the compressor into the oil recovery flow path 82. Therefore, the stagnation of the liquid in the vicinity of the second check valve 83 disposed in the oil recovery flow path 82 is suppressed, so that the non-return failure of the second check valve 83 can be prevented. That is, the reliability of the second check valve 83 can be reliably ensured.

In addition, according to the present embodiment, the linear fourth recovery passage hole 88 for disposing the second check valve 83 is provided with the sixth external opening 88 b, and the second recovery valve hole 88 is smaller than the second check valve 83. Adjacent to the large diameter portion 95 having the large diameter and the medium diameter portion 96 adjacent to the large diameter portion 95 and having a diameter smaller than the large diameter portion 95 and larger than the second check valve 83; Since the second check valve 83 is replaced by the small diameter portion 97 having a smaller diameter than the second check valve 83, the positioning of the second check valve 83 in the fourth recovery passage hole 88 is It is easy and easy to insert and remove the second check valve 83 through the sixth outer opening 88b. That is, the second check valve 83 can be replaced very easily.

Further, according to the present embodiment, four (plural) linear first recovery passage holes 85 having the

external openings

85b, 86a, 87a, 88b opened to the outside of the casing 6, a second recovery flow Since the oil recovery passage 82 is constituted by the passage hole 86, the third recovery passage hole 87, and the fourth recovery passage hole 88, the oil recovery passage 82 is formed by forming a plurality of holes in the wall portion of the casing 6. It is possible. Therefore, the manufacturing cost of the oil recovery system 80 can be further reduced.

Furthermore, according to the present embodiment, the second check valve 83 is positioned higher than the male rotor 4 and closer to the recovery side opening 88a than the storage side opening 85a in the oil recovery flow path 82. Therefore, even if the lubricating oil leaked from the shaft seal device 12 overflows the recovery groove 81, the second check valve 83 is not affected by the lubricant oil leaked from the shaft seal device 12. Therefore, the reliability of the second check valve 83 can be secured.

[Other Embodiments]
In the above-described embodiment, an example in which the present invention is applied to a male and female screw rotor is shown, but the present invention can also be applied to a single rotor or triple rotor type screw compressor.

Further, the present invention is not limited to the present embodiment, and includes various modifications. The embodiments described above are described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. For example, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is also possible to add, delete, and replace other configurations for part of the configurations of the respective embodiments.

For example, in the above-described embodiment, an example of the configuration using the snap rings 74 and 99 for attaching the first check valve 62 and the second check valve 83 is shown. A configuration using a toothed washer instead of the above is also possible. Moreover, while screwing in the outer peripheral part of the 1st non-return valve 62 and the 2nd non-return valve 83, the inner peripheral surface of the flow-path holes 65 and 88 which arrange | positions the 1st non-return valve 62 and the 2nd non-return valve 83. It is also possible that the first check valve and the second check valve are detachably mounted by screwing the screw.

In the above-described embodiment, the intake bypass passage 61 is constituted by two passage holes of the first bypass passage hole 64 and the second bypass passage hole 65. However, the intake throttle valve Depending on the shape of the wall portion of the second housing 41, three or more flow path holes may be used. Similarly, an example in which the oil recovery flow passage 82 is configured by four flow passage holes of a first recovery flow passage hole 85, a second recovery flow passage hole 86, a third recovery flow passage hole 87, and a fourth recovery flow passage hole 88 However, depending on the shape of the wall portion of the casing 6, it is also possible to configure by any plurality of flow passage holes.

In the embodiment described above, the first check valve 62 is disposed in the second bypass passage hole 65 of the intake bypass passage 61, but the arrangement position of the first check valve 62 is It is optional in the region in the intake bypass channel 61 where the liquid ejected from the meshing portion of the male and

female rotors

4 and 5 does not stagnate when the compressor is operated. Similarly, although an example in which the second check valve 83 is disposed in the fourth recovery passage hole 88 of the oil recovery passage 82 has been shown, the arrangement position of the second check valve 83 is determined by the male and female at the time of operation of the compressor. In the area within the oil recovery flow path 82 in which the retention of the liquid ejected from the meshing portion of the

rotors

4 and 5 does not occur, and in the oil recovery flow path 82 not affected by the lubricating oil leaking from the shaft sealing device 12 It is optional in the area.

In the embodiment described above, an example of the configuration in which the first shielding portion 76 is provided in the suction chamber 28 is shown, but at a position where the liquid spouted into the suction chamber 28 does not easily enter during operation of the compressor. When the intake bypass channel 61 can be incorporated in the housing 41, the first shielding portion 76 can be omitted. Similarly, although the example of the structure which provided the 2nd shielding part 101 in the suction chamber 28 was shown, when the oil collection | recovery flow path 82 can be incorporated in the casing 6 in the position where the liquid which ejects into the suction chamber 28 does not easily invade. The second shielding unit 101 can be omitted.

2 ... suction throttle valve, 4 ... male rotor (screw rotor), 5 ... female rotor (screw rotor), 6 ... casing, 9 ... shaft portion, 10 ... suction side bearing (bearing), 12 ... shaft sealing device, 16 ... Suction side bearing (bearing), 27 ... suction port, 28 ... suction chamber, 41 ... housing, 42 ... suction flow path, 60 ... intake bypass system, 61 ... intake bypass flow path, 62 ... first check valve, 64 ... First bypass flow passage hole (bypass flow passage hole), 64a: primary side opening (first opening), 64b: first external opening (outside opening), 65: second bypass flow passage (bypass flow) Road hole), 65a ... secondary side opening (second opening), 65b ... second external opening (third opening, external opening) 70 ... large diameter, 71 ... middle diameter, 72 ... Small diameter portion, 76 ... first shielding portion ( Covered portion) 80: Oil recovery system 81: Recovery groove portion (oil storage portion) 82: Oil recovery flow passage 83: Second check valve (check valve) 85: First recovery flow passage hole (recovery Flow path hole), 85a ... storage side opening (fourth opening, first opening), 85b ... third external opening (outside opening), 86 ... second recovery flow path hole (recovery flow path hole) 86a ... fourth external opening (external opening), 87 ... third recovery channel hole (recovery channel hole), 87a ... fifth external aperture (external opening), 88 ... fourth recovery channel hole (Recovery flow passage hole) 88a: recovery side opening (fifth opening, second opening) 88b: sixth external opening (sixth opening, third opening, external opening) 95: Large diameter portion 96 Medium diameter portion 97 Small diameter portion 101 Second shielding portion (shielding portion).

Claims

A screw rotor for compressing the gas,
A bearing rotatably supporting the screw rotor;
A casing which accommodates the screw rotor and the bearing and has a suction port for sucking in gas and a suction chamber connected to the suction port;
A suction throttle valve having a housing disposed at the suction port and forming a suction flow passage communicating with the suction port;
An intake bypass system that communicates the primary side and the secondary side of the suction throttle valve;
The intake bypass system is
An intake bypass channel provided on a wall of the housing and having a first opening opening on the primary side of the suction throttle valve and a second opening opening on the secondary side;
A first non-return valve disposed in the intake bypass passage to allow flow from the primary side to the secondary side of the suction throttle valve while blocking flow from the secondary side to the primary side of the suction throttle valve With a valve,
The fluid intake screw compressor, wherein the intake bypass passage has a third opening that is open to the outside of the housing and in which the first check valve can be inserted and extracted.
In the liquid feed screw compressor according to claim 1,
The liquid supply system according to claim 1, further comprising: a shielding portion provided between the second opening of the intake bypass flow path and the screw rotor so as to cover the second opening in a separated state. Screw compressor.
In the liquid feed screw compressor according to claim 1,
The intake bypass channel includes a straight bypass channel hole having the third opening and in which the first check valve is disposed,
The bypass passage hole is
A large diameter portion having the third opening and having a diameter larger than that of the first check valve;
An intermediate diameter portion adjacent to the large diameter portion and having a diameter smaller than the large diameter portion and larger than the first check valve;
A liquid feed type screw compressor comprising: a small diameter portion adjacent to the middle diameter portion and smaller in diameter than the first check valve.
In the liquid feed screw compressor according to claim 1,
The intake bypass channel is composed of a plurality of linearly extending bypass channel holes,
The plurality of bypass passage holes each have an external opening that opens to the outside of the housing.
The liquid feed screw compressor according to any one of claims 1 to 4, wherein
A shaft seal device for sealing a gap between the shaft portion of the screw rotor and the casing;
An oil recovery system for recovering the lubricating oil leaked from the shaft sealing device into the suction chamber;
The oil recovery system is
An oil storage portion provided in the casing and capable of temporarily storing the lubricating oil leaking from the shaft sealing device;
An oil recovery channel provided at a wall portion of the casing and having a fourth opening opening to the oil storage portion side and a fifth opening opening to the suction chamber side;
A second check valve disposed in the oil recovery flow path, permitting flow from the oil storage portion side to the suction chamber side, and blocking flow from the suction chamber side to the oil storage portion side; Have
The fluid recovery screw compressor, wherein the oil recovery passage has a sixth opening that is open to the outside of the casing and in which the second check valve can be inserted and extracted.
A screw rotor for compressing the gas,
A bearing rotatably supporting the screw rotor and supplied with lubricating oil;
A casing which accommodates the screw rotor and the bearing and has a suction port for sucking in gas and a suction chamber connected to the suction port;
A shaft seal device for sealing a gap between the shaft portion of the screw rotor and the casing;
An oil recovery system for recovering the lubricating oil leaked from the shaft seal device into the suction chamber;
The oil recovery system is
An oil storage portion provided in the casing and capable of temporarily storing the lubricating oil leaking from the shaft sealing device;
An oil recovery channel provided on a wall of the casing and having a first opening that opens to the oil storage portion and a second opening that opens to the suction chamber;
There is a check valve which is disposed in the oil recovery flow passage and allows the flow from the oil storage portion side to the suction chamber side, while blocking the flow from the suction chamber side to the oil storage portion side. And
The liquid recovery type screw compressor, wherein the oil recovery passage has a third opening that is open to the outside of the casing and in which the check valve can be inserted and extracted.
In the liquid feed screw compressor according to claim 6,
The liquid supply system according to claim 1, further comprising a shielding portion provided between the second opening of the oil recovery flow passage and the screw rotor so as to cover the second opening in a separated state. Screw compressor.
In the liquid feed screw compressor according to claim 6,
The liquid supply liquid is characterized in that the check valve is disposed at a position higher than the screw rotor and at a position closer to the second opening than the first opening in the oil recovery channel. Screw compressor.
In the liquid feed screw compressor according to claim 6,
The oil recovery channel includes the linear recovery channel hole having the third opening and in which the check valve is disposed,
The recovery channel hole is
A large diameter portion having the third opening and having a diameter larger than the check valve;
An intermediate diameter portion adjacent to the large diameter portion and having a diameter smaller than the large diameter portion and larger than the check valve;
A liquid feed type screw compressor comprising: a small diameter portion adjacent to the medium diameter portion and having a diameter smaller than the check valve.
In the liquid feed screw compressor according to claim 6,
The oil recovery channel is composed of a plurality of recovery channel holes extending in a straight line,
The plurality of recovery flow path holes each have an external opening that opens to the outside of the casing.